This invention relates to a new plywood core block.
Many kinds of plywood have hitherto been provided afford desired rigidity, hardness, or strength thereto. Among these known types of plywood, there has recently been provided a rigid plywood which comprises a core block having a number of thin and narrow wood strips adhered side by side with their grains arranging in the same direction, and relatively wide backing plates attached to the upper and lower surfaces of the core block.
However, to form a plywood of this type, a number of wood strips have to be cut out of a thin wood sheet to have a predetermined width, and the cut-out wood strips have to be arranged side by side and adhered in close contact with each other. Accordingly, the method for forming the known plywood is not efficient in actual practice due to the cutting and arranging processes.
Further, it is very difficult in the known method to form a core block having desired flexibility, lightness and strength without substantially impairing the rigidity thereof, due to the difficulty of arranging the wood strips with desired spacing therebetween.
Moreover, when the core block for the plywood is formed from a wood sheet which has been cut out of a wood material by means of a veneer lathe or a veneer slicer, irregular shaped front and rear ends of the wood sheet have to be cut away, so that the yield rate of the core block from the wood material is relatively low.
Accordingly, a main object of the present invention is to provide a new plywood core block which avoids the above disadvantages of the known core block.
Another object of the present invention is to provide a new core block for a plywood having desired flexibility and lightness without substantially impairing the rigidity thereof.
A further object of the present invention is to provide a plywood core block which may be easily and effectively formed.
Still another object of the present invention is to provide a plywood core block which may be formed from a wood material at a high yield rate.